Milliampere and voltage meter



July 5, 1932. J. wEBBER ET AL MILLIAMPERE AND VOLTAGE METER 2sheets-sheet 1 Filed May 10 1930 July 5, 1932 .1. WEBB'ER ET Al.

MILLIAMPERE AND VOLTAGE METER Filedl May 1o, 19:50

2 Sheets-Sheet 2 gyf WW tory drawings Patented July 5, 1932 UNITEDVs'rilrrrs PATEN 'r oFFlcE JOSEPH WEBBER, 0F MANCHESTER, AND JOSEPHCOOPER, MABKET DRAYTON, LAND, SSIGNORS To PROVINCIAL- INCANDESCENT:FITTINGS- ComANY 'LIMITED, @F MANCHESTER, ENGLAND, BRITISH COMPANY 'f pmILLIAMPERE-AND VOLTAGE METER -pplioation led May 10, 1930, Serial No.451,357, and in Great Britain September 4, 1929.

This invention relates to instruments for use in the testing of wirelessor other electrical apparatus and has for its object to provide a new orimproved instrument adapted for the testing of the filament of athermionic valve and also if desired for the testing of the high and lowtension batteries or other sources of high and low tension current.

The invention comprises a meter or measuring instrument incorporating abattery, 'af

-voltmeter and a `valve holder arranged so that when a valve isplaced'in the holder, a reading is given by the voltmeter if the valvefilament is in order.

The invention further comprises the incorporation of the valve holderand battery in an instrument arranged for the testing of high and lowtensionr batteries, the said instrument having one indicating fingermoving over a multiple scale. f

Referringto the accompanying explana- Figure 1 is a rear view of a valvefilament v testing instrument with lthe back cover removed and withcertain parts in section', constructed 1n one convenlent form.

p Figure 2 is-a sectional side elevation, Figvure 3 a rear view withcertain internal parts shown in dotted lines and Figure 4 a, front viewof the instrument shown in Figure l.

Figuref is a rear view with the cover removed and Figure 6 a rear viewwith the cover in place but with certainI internal parts shown' indotted; lines, of an instrument adapted for the testing of high and lowtenthermionic valves. f

Figure 7' is a rear view with the cover rey sion batteries in additionto the ilaments of moved and Figure 8 a sectional side elevai tion of amodified construction ment shown in Figures 5 and 6.

Figure 9 shows the dial or Lface of the inof the instru-v l strumentsshown in Figures 5, 6, 7 and 8.

The same reference letters in the dierent views indicate the same orsimilar parts.

In Figures 1-4, the instrument which is of the watch typecomprises acasing a into whlchv projects ametal ttubek b' adapted to contain anelectric battery c. The cap dof the tube b fits into thecase a and makescontact with the terminal e' of the battery.

blade spring f makes contact with the other pole of the battery and hasa lead g connected thereto and to one end of the voltmeter coil 7i, thelinger z' ofthe voltmeter having the movingiron secured thereto in theknown manner. The otherend of the coil It is` connected by the lead j tothe blade le. m the e, whilst the blade 1' makes contact with the blade7c.

Thus when a valve has its terminals placed in the holes 0p,the-,filament thereof is in circuit with the battery c and the voltmetercoilv L. Therefore, if the filament is intact, y

a reading will be given b the pointer z' uponl the scale s on the -faceo the instrument.

If desired, a cap similar to d may be provided in the case at the sideopposite to the other end of the tube b so that when the additional capis removed, atool or instrument may be inserted to pless the battery outof thetube b when it-has to be renewed.

The instrument sho/wn in Figures 5 and 6 is adaptedA for testing thevoltage ,of highl and low tension batteries and the current inmilliamperes of the highftension battery. For'this purpose a iexiblelead t is taken from the` ring pillar u which is insulated y. If the twoterminals Iv and w are connected in circuit with a high tension battery,the flow of .current in milliamperes will be 1nd1- cated by theinstrument.- The internal cir- .of a low tension battery can be made,the inj ternal circuit comprising the blade f, the

coil L andthe pillar u. For testing a highv from the casing a; Upon thecasing are also arranged the insulated terminals, o, fw, and

tension battery for voltage, the lead t and the terminal a: are used,the internal circuit then consisting of 'the resistance coil z, the coilh and the pillar u. To test the lament 5f of a thermionic valve, thelatter is plugged into the back plate of the instrument when theinternal circuit completed by the filament of the valve comprises theblade g,

tube b and one pole of the battery in the tube,

the other pole of the battery the spring blade f, the coil k, the pillaru and the blade 2 which engages a part upon said pillar When the coveris in place and Which is secured upon one of the terminal bushes o onthe inner side of the rear plate.

A In place of the terminal posts o, w, a: and y,

We may employ flexible leads for testing purposes.

` In the instrument shown in Figures 7 and 8, 2 the battery c is carriedin clips 01 upon a plate or division 9 Within the casing, such platealso having the sockets o for the thermionic valve plugs projectingtherefrom. The rear cover n fits over the ends of such sockets as shown.

In Figure 9, 5 indicates the scale associated with the testing of theiilament of the thermionic valve, 6 the scale associated With thetesting of the voltage of a low tension battery, 7 the scale associatedWiththe testing of the 3.0 voltage of a high tension battery and 8 thescale for testing the current in milliamperes of the high tensionbattery.

1. An electric testing instrument of the watch case type incorporatingWithin its casing, a battery, a voltmeter movement, and a valve holderarranged so that When a thermionic valve is placed in the holder, areading is given by the voltmeter if the valve lilament is in order.

2. An electric testing instrument of the- Watch ease type as -claimed inclaim vl, in which the battery is in a tube extending across theinstrument and the valve holder is constituted by the rear cover of theinstrument, with blade springs upon such cover for completing thetesting circuit.

3. In an electric testing instrument of the Watch case type as claimedin claim 1 and in Which the voltmeterserves ralso for testing high and10W tension batteries for voltage and high tension circuits forcurrents, the` mounting of the battery in clips upon a plate, ordivision Wall Within the instrument, the sockets for the 4therrnionicvalve filament plugs projecting through the rearcover of vtheinstrument.

i In testimony whereof We have signed our names to this specification.

` JOSEPH WEBBER.

JOSEPH COOPER.

